1. Field of the Invention
The present invention relates to an artificial spacer for keeping adjacent vertebrae spaced from each other after a faulty intervertebral disk has been removed from cervical vertebrae or lumbar vertebrae of a vertebral column.
2. Description of the Relevant Art
In a known surgical procedure to be carried out on a patient who is suffering a spinal failure such as the herniation of an intervertebral disk, the faulty intervertebral disk is removed anteriorly of the patient, and a vertebra filler or spacer is inserted between the vertebrae that are positioned above and below the removed intervertebral disk.
Vertebra fillers that are known for use in the above procedure include autografts taken from the patients' iliac bones, and bioceramic bones (allografts) of alumina, hydroxy apatite, or the like.
According to the above medical operation, confronting portions of the vertebrae positioned superiorly and interiorly of the removed intervertebral disk are cut off, and the vertebra spacer is inserted between the vertebrae from the anterior side of the patient, filling up the space between the vertebrae. The vertebra filler is effective to hold the vertebrae in position against compressive forces applied thereto. However, it is less effective to hold the vertebrae in position when tensile forces or forces normal to the compressive or tensile forces are applied thereto.